A tank-venting apparatus typically includes the following features: a tank, a tank-venting valve and an adsorption filter. The adsorption filter is connected to the tank via a supply line, has a connecting line for connecting the adsorption filter to the tank-venting valve and has a venting line.
An underpressure is generated in the valve line in order to vent the tank and to scavenge the adsorption filter with fresh air. The apparatus is used for an internal combustion engine without a charger in that the tank-venting valve is opened with the tank-venting valve being connected into the valve line connected to the intake pipe of the engine. For such an engine, except for full load, an underpressure is always present in the intake pipe which is adequate for venting the apparatus. In contrast, an overpressure is present in the intake pipe in an internal combustion engine equipped with a charger. For this reason, tank-venting apparatus which are to be operated on such an engine are provided with a pump in the valve line. This pump pumps vapor from the apparatus into the intake pipe. These conventional apparatus, however, have the disadvantage that they are relatively expensive because of the required pump.